How the MRP Planning Run Works --- MM MRP--CBP planning

In consumption-based planning, the following MRP procedures are available: Reorder point procedure Forecast-based planning Time-phased materials planning

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1. Reorder Point Planning (REORDER) (MRP Type VB, Reorder Level)

When Available Stock falls below reorder level, planned orders are generated in the planning run to order up to reorder level. Safety Stock requirement is just for information.

Available Stock = Plant Stock + Receipts

2. Reorder Point Planning + Requirements (REORDERREQS) (MRP Type V1,Reorder Level)

When Available stock falls below reorder level, planned orders are generated in the planning run to order up to reorder level. Safety stock requirement is just for information. The difference here is that sales orders and reservations are also taken into account.

Available Stock = Plant Stock + Receipts - (Sales Orders + Reservations)

3. Forecast Based Planning (FORECAST) (MRP Type VV, Create Forecast)

System only considers forecast requirements (any other requirements are not considered). Planned orders are proposed when available stock is less than forecast requirements.

Available Stock = Plant stock - Safety Stock + Receipts - Forecast Requirements

4. Time Phased Planning (TIMEPLAN) (MRP Type R1, Planning Cycle, Create Forecast)

Material is planned according to same cycle in which it is delivered ie the material is not planned during the normal MRP run. The material have to be planned using a separate MRP run.

Available Stock = (Plant stock - Safety Stock + Receipts - Forecast Requirements) within the planning cycle.

5. MRP Planned (PDFORECAST) (MRP Type PD, Optional Create Forecast)

System checks every requirement to determine whether they are covered by available warehouse stock and/or receipts.

Available Stock = Plant stock - Safety Stock + Receipts - All Requirements

1. MRP Group (MRP1) - Group common MRP materials together - The MRP group contains all the materials from the point of view of MRP for assigning special control parameters for the total planning run. These control parameters include, for example, the strategy group, the consumption mode, and the planning horizon.
2. MRP Type (MRP1) - Planning Method.
3. Reorder Point (MRP1) - For Reorder Point Planning Methods
4. Planning Time Fence (MRP1) - Restrict Planning Activities within the Time Fence

Planning time fence主要是为了保证近期计划的稳定性，避免系统自动修改近期计划，PLANNING TIME FENCE 设定是按天数进行，例如果有设定PLANNING TIME FENCE为5的话，执行MRP时，如果有新需求在PLANNING TIME FENCE 之内（5天之内）的话，系统将产生新的PLAN ODER，
但是会放在PLANNING TIME FENCE之外的第一天（即第六天）。并提供例外信息提醒计划员。

1. Planning Cycle (MRP1) - Only for Time Phased Planning : Key that determines the day on which the material is planned and ordered. The planning cycle is a planning calendar that is defined in Customizing for MRP.
2. MRP Controller (MRP1) - Planner for the material.
3. Lot Sizing (MRP1) - Lot Size determination
4. Storage Cost Indicators (MRP1) - For Optimum Lot sizing Only
5. Ordering Costs (MRP1)- For Optimum Lot Sizing Only
6. Assembly Scrap (MRP1) - For Assembly Scrap Only
7. Procurement Type (MRP2) - Make or Buy Indicator.

Indicator that defines how the material is procured. The following procurements types are possible:

o The material is produced in-house.

o The material is procured externally.

o The material can be both produced in-house and procured externally.

1. Special Procurement (MRP2) - For stock transfers, phantoms etc. Allows you to define the procurement type more exactly. The system determines the procurement type from the material type.
2. Quota Arrangement (MRP2) - Splitting of Quota for internal and/or external procurement (MM will handle this)
3. Lead Times (GR and Planned Delivery Time) (MRP2) - Receiving and Purchasing Lead Times
4. Scheduling Margin Key (MRP2) - How external or internal procurement is scheduled

计划边际码（Scheduling Margin Key）是定义计划扩展的一些时间的，其中计划边际码涉及的字段有四个，分别是：未清期间、产前缓冲时间、产后缓冲时间、下达期间（时间单位均为天）。

未清期间Opening Period：是指计划转换日期需要比开始日期提前几天，如果本来计划开始日期是20日，未清期间设置为2，那么计划转换日期就应该是18日。

产前(或产后)缓冲时间Floating after/before production：指在正直的生产开始之前（或完成之后）需要经过多少天数的等待，产前（产后）缓冲时间的设置会增加生产周期。

下达期间release Period：指计划开始下达到开始生产之间的天数。如果下达期间为一天，那么开始下达日期就会比生产开始日期提前一天。

1. Safety Stock (MRP2) - Safety Stock
2. Forecast (MRP3 and Forecasting) - Mainly for Forecast Based Planning, ReOrder Point Planning and Time pahsed Planning
3. Planning Strategy (MRP3) - Mainly for Finished Goods - to be decided by APO
4. Availability Check (MRP3) - ATP logic for components - to be decided by ZL. For Finished Goods - to be decided by APO.
5. Discontinuation (MRP4) - Discontinuation by material across all BOMs
6. Component Scrap (MRP4) - Component Scrap
7. Requirements Grouping (MRP4) - Group requirements for planning or display
8. Storage Location MRP (MRP4) - Only if storage MRP is required

Process Flow

1. When you start the planning run, the system uses the MRP date recorded in the planning file to check which materials are actually to be planned. The planning date is calculated using the planning cycle.
2. The system calculates requirements. It also then determines a time interval. This time interval must take into account that the material has to cover all requirements up to the next MRP date including the delivery time. The requirements are calculated according to the following formula:
   1. "Forecast requirements - or other requirements in the interval (interval = planning cycle + purchasing processing time + planned delivery time + goods receipt processing time) + safety stock"
3. In the net requirements calculation, the system reduces the requirements calculated in the interval by stock and firmed receipts. The remaining quantity is equal to the shortage quantity.
4. If you use the lot-for-lot, the system creates a procurement proposal for the amount of the shortage quantity. If you have selected another lot-sizing procedure, the quantity in the order proposal depends on the lot-sizing procedure.

During the calculation, the system takes for granted that the firmed receipts lie in the interval in question. It does not matter whether the firmed receipts are available at the beginning or not until the end of the interval. This means that a temporary shortage may exist, however, this is accepted.

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